# How does the "Preview" tool work?

Gold Member
Hi PF

First I must apologize for posting a trivial question; I did it when published "Advice to obtain the domain of compound functions": the answer was given at the same time. I also typed bad, I forgot one delimiter.
How works Preview tool? How can I make use of it to obtain a preview as many times as I need? I didn't manage to display it more that one time.

Regards!